Optical scanner is widely used as an input device for documents, graphics and images in the office automation environment. It could become even more popular once the optical character recognition (OCR) technology being included. Conventional optical scanner is generally formed in a rectangular body (referring to FIG. 1), including mainly an upper case (11), a supporting frame (12) and a base (13). A cover board (14) is disposed above upper case (11), upper case (11) is screwed with supporting frame (12) which is further screwed with base (13) to form the main structure of a scanner. Scanning head (120) captures the digital signals of the scanning documents and transmits to main circuit board (130) for data processing and input output function. Main circuit board (130) is located below scanning head (120) and is disposed inside of base (13)
The structure of conventional optical scanner set forth above has drawbacks in actual utilization. The tightly screwing among the main components making repairs and maintenance difficult and time-consuming as it usually takes three or four dismantling steps to separate the key components. The repetitive separation and assembly tend to damage parts and their reliability. The scanning head also tends to expose to outside dusts and dirts, and impair its effective life.
There are some structural improvement to address the issue set forth above as illustrating in FIG. 2. Main circuit board (21) is disposed on a movable base board (20) which can be drawn out from under base frame (30), movable base board (20) is mounting and moving along a pair of guiding rail (31) which is fixed on base frame (30). Power supply circuit board (22) is disposed on one side of movable base board (20). The repairs and maintenance of circuits can be easily done without dismantling the main structural components. In the mean time the semi-opening design of movable board allows heat dissipating more effectively.
Although movable base board have advantages described above, it is located under the bottom of a scanner, and make repairs and maintenance awkward when no drawing means being provided.